CHAPTER XXVII 



EFFECT OF ANAESTHETICS ON GEOTROPIC RESPONSE 



Geotropic response of growing organs has been shown to 

 be due to differential growth induced in the upper and lower 

 sides of the organ, there being a retardation of growth in 

 the directly stimulated upper side. The intensity of response 

 will therefore depend : 



1. On the normal activity of growth ; 



2. On the effect of season and of various external agents 



which enhance or retard the normal rate of growth. 



It has been shown, for instance, that growth is modified 

 by anaesthetics in a characteristic manner. Anaesthetic 

 agents may, according to their action, be divided into three 

 classes : 



1. Strong anaesthetics, such as chloroform, induce a 

 preliminary acceleration of growth, followed by arrest. 

 Continued action causes a spasmodic death-contraction. 



2. Ether is less toxic than chloroform ; a small dose of 

 ether enhances the rate of growth. It is only under pro- 

 longed apphcation that it induces retardation or arrest. 



3. Carbon dioxide is a mild anaesthetic, the immediate 

 effect of which is an enhancement of growth. Its con- 

 tinuous action is followed by a decline and arrest of growth. 

 Prolonged apphcation often induces actual contraction. 



I describe the effect of season and of various anaesthetics 

 in modifying geotropic response. 



